The present invention relates to a method for the processing of data called cells, coming from the adaptation layer for transmission according to an ATM (asynchronous transfer mode) type of asynchronous transmission.
It may be recalled that transmission in ATM mode is done by the transfer of blocks of information having a constant length. The elementary quantity of useful information transmitted is 48 bytes. The information block transmitted in ATM is called a cell and is identified by a five-byte label called a header. The total length of a cell is therefore 53 bytes. It may also be recalled that the protocol of transmission according to an asynchronous mode such as the ATM makes use of different layers for the transfer of information and, notably, makes use of an adaptation layer for the ATM mode such as the AAL5 layer defined by the CCITT I362 and I363 recommendations.
The adaptation layer makes it possible, at transmission, to subdivide a message into bits that can be conveyed by ATM cells and then, at reception, to retrieve the constituent cells of one and the same message from the flow of ATM cells received in order to reconstruct the message.
The reception of the ATM flow is done by means of a reception terminal capable of processing the cells in order to reconstitute the messages and enable their exploitation. The presently used transceiver terminals carry out this segmentation and this reassembling of messages in a working pre-memory. Once the message is received, processed and reassembled, the processor of the receiver terminal is informed thereof and has to carry out the retransmission of said message to its own memory so as to be capable of exploiting it. This type of embodiment is relatively simple to design but dictates an additional step for the transfer of the data with all the appropriate additional, material resources, namely intermediate memories and read/write and control devices.